Help needed :) A 55 kg roller coaster car is 70 m high, when it reaches the ground, its velocity is 15.5
m/s. Calculate the amount of energy lost due to friction?

There are multiple tuning forks present in the room, and annie strikes one with a natural frequency of 400 hz. which of these other tuning forks will begin to vibrate through resonance and make the sound louder? a 200 hz tuning fork a 400 hz tuning fork a 800 hz tuning fork a 1600 hz tuning fork